Updating the ignition on a Bat action.

[Alex Wheeler]

Im building a 2000yd rifle for a customer on a model L action. The bolt is older and has the old style threaded shroud. The firing pins were light and so were the springs back then, they also guided the firing pin differently and had shallow cocking ramps that only allow about .210" of firing pin fall without adding cock on close. I much prefer the new style ignition especially on a 2kyd rifle hitting magnum primers. I have done this before and figured Id take a couple pictures as it is kind of interesting and Bat will not do the updates on these older bolts.

I ordered all the new parts, luckily they really didnt change things too much. I modify the shroud by setting it up in the lathe and cutting threads on it, fitting them very tightly. This works out very well, in fact the ones I have done had absolutely no drag on the firing pins. The threads in the bolts have been very straight. You can see the new parts on the left and old assembly on the right with the before and after of a new shroud.






The next step was to re cut the cocking cam helix so I can time the action and gain some firing pin fall. Before and after,



I can then time the ignition and fit the rest of the parts and modify the action to allow for the increased pin fall. I ended up with .242" of firing pin fall with a neutral handoff (no cock on close or fall on close). I made up a 22lb. spring for it and it opens and closes very nicely. It sounds much better than before. Its nice to get some unusual jobs from time to time to get the brain going. Its quite a bit of work, but I have gotten the before and after feedback of these mods and it has cured a handful of rifles accuracy problems, typically unexplained vertical fliers.

 

[DiffEQ]

Thanks for sharing. That new spring looks quite beefier. What is the difference in poundage?

 

[Alex Wheeler]

I will have to measure the old one but typically they were in the 18-19 lb range.

 

[jackieschmidt]

Alex, As you might remember, I converted my Bat M to a screw in shroud a while back. It cured it’s tendency to spit shots. It was a big project, but it proved to be worth it.

Just my opinion, but I think Bat should have stuck with the screw in shroud.

By the way. Nice work.

 

[Alex Wheeler]

Thanks Jackie, I actually have a preference to the non threaded shrouds only for the reason that in my experiance the manufacturers fit them better than they do with threads. Many times the threads are not straight in the bolt and the fit is loose. If they were all straight and fit well, Id like them a lot more. I would guess your action shot better because you fit the parts well. I have oversized shrouds that I fit to the non threaded bolts as well. The ignition can make or break a rifle as you know. But I have to say these "retro fit" threaded bolts have been as good as I have seen. Bat did do the threaded shrouds VERY well.

 

[DangerRanger]

these posts are great, you see so little about ignition system design/improvement online.

Bit of a tangent but ignition related, do you prefer different diameter firing pins for the bigger cases?

 

[Alex Wheeler]

I assume you mean firing pin tips? I have not directly tested this, so I cant comment with authority. But Bats are all .070" and many others are .062" or .075". I would not say I have had anything to lead me to think there was an accuracy issue with either. Even in customs the strike can be off center so the radius on the tip and diameter can play a role in hitting center. I have a lot of things I still want to test, it just takes time and money

 

[Hal]

Thank for sharing and pictures are the icing on the cake.
It's nice to see all the work you go through to wring out every little bit of accuracy.
Let us know how it shoots.

Hal

 

[boltfluter]

Nicely done Alex! Sometimes a few pics are worth a thousand words.

Paul

 

[DaveTooley]

When I start talking to industry about ignition their eyes glaze over, they get weak in the knees and they change the subject.

 

[AlNyhus]

When I start talking to industry about ignition their eyes glaze over, they get weak in the knees and they change the subject.

Isn't that the truth? Some years ago, a group of us has dinner with an up and coming action maker. When asked about pin fall and spring weight, he didn't want to address it....finally committing to .210 pin travel and an 18 lb spring. I put my foot in my mouth by opining that an action maker should start with the ignition and build everything else around it....like Kelbly's did using the Remington 700 based system. He didn't like it.

And....surprise, surprise.....those action had all sorts of ignition issues. There's a NIB one sitting in town here that I've been tempted to buy and try my hand at fixing it.

 

[Alex Wheeler]

It is true, especially some of the newer actions coming out today. You sure can make them feel great with shallow cocking ramps and light springs. That sells actions. But they do have a lot of problems. One of the big prs actions has about .180" of fall after timed for no cock on close (which many guys do including the factory) I made the decision early on to decline fixing them because the number of requests I was getting. I would have been overwhelmed with them. Unfortunately some do not realize theres more to the ignition than just setting off the primers. Accuracy falls off long before you will see actual misfires or hang fires. Even worse an action with ignition problems will still occasionally shoot tiny groups, but it wont agg. well and may fool you into thinking there isnt a problem and you just missed a condition or some other driver error.

 

[hoz53]

Im building a 2000yd rifle for a customer on a model L action. The bolt is older and has the old style threaded shroud. The firing pins were light and so were the springs back then, they also guided the firing pin differently and had shallow cocking ramps that only allow about .210" of firing pin fall without adding cock on close. I much prefer the new style ignition especially on a 2kyd rifle hitting magnum primers. I have done this before and figured Id take a couple pictures as it is kind of interesting and Bat will not do the updates on these older bolts.

I ordered all the new parts, luckily they really didnt change things too much. I modify the shroud by setting it up in the lathe and cutting threads on it, fitting them very tightly. This works out very well, in fact the ones I have done had absolutely no drag on the firing pins. The threads in the bolts have been very straight. You can see the new parts on the left and old assembly on the right with the before and after of a new shroud.


View attachment 1283141

View attachment 1283142

The next step was to re cut the cocking cam helix so I can time the action and gain some firing pin fall. Before and after,
View attachment 1283144
View attachment 1283145

I can then time the ignition and fit the rest of the parts and modify the action to allow for the increased pin fall. I ended up with .242" of firing pin fall with a neutral handoff (no cock on close or fall on close). I made up a 22lb. spring for it and it opens and closes very nicely. It sounds much better than before. Its nice to get some unusual jobs from time to time to get the brain going. Its quite a bit of work, but I have gotten the before and after feedback of these mods and it has cured a handful of rifles accuracy problems, typically unexplained vertical fliers. View attachment 1283146

thanks Alex for sharing that—

 

[AlNyhus]

It is true, especially some of the newer actions coming out today. You sure can make them feel great with shallow cocking ramps and light springs. That sells actions. But they do have a lot of problems. One of the big prs actions has about .180" of fall after timed for no cock on close.....

Alex, on that particular action....what stops the forward travel of the firing pin? -Al

 

[Jud96]

Nice work Alex. Cutting the closing helix is tricky stuff, especially without CNC equipment. Very impressive work

 

[Alex Wheeler]

Alex, on that particular action....what stops the forward travel of the firing pin? -Al

Al, it stops on the firing pin collar like most but I have not seen all the actions out there if your thinking of a different one.

 

[accuracyman]

Very nice work Alex. I was wondering about the modifications many make on the slot in the shroud where the cocking piece rides. I see some Benchrest gunsmiths taking relief cuts on the bottom and sides of this slot to reduce the amount of friction on the cocking piece. What is your take on this modification?

I have a very early BAT DS that I am considering having this modification done since they are obviously striving for consistent ignition.

 

[Alex Wheeler]

That was common on the old style shrouds. In the new style the cocking piece does not bear load inside the shroud.

 

[Alex Wheeler]

these posts are great, you see so little about ignition system design/improvement online.

Bit of a tangent but ignition related, do you prefer different diameter firing pins for the bigger cases?

As a follow up, I got around to doing some ignition and spring testing in the LR Neuvo. We did try a .062 and it did not shoot as well as the stock .070. Now, I'm sure there is more than one factor at play. But at least that primer preferred that size. It also shot quite different with a range of springs. There's more to be done, we are still working on it.

 

[Borisserge]

Thank you for sharing your knowledge and experience.
This sort of insight always amazes me, and would love to fine tune further the screw in shrouded Bat M I have.
The Tenon threads on mine wasn't 100% perfect, and the firing pin fall could be improved.

I won't dabble too much more as it shoots exceptionally well, but does throw the odd bullet out of group.
Can you make it shoot worse by trying to improve its flyers?